1. Field of the Invention
The present invention relates generally to a process cartridge in which development associated members such as a development roller are made as a unit, and more particularly, to a process cartridge having an improved detachability operability and to an image forming apparatus using the same.
2. Description of the Related Art
Conventionally, in this type of image forming apparatus, elements or components for use in image formation such as a toner hopper, a development roller, a photoreceptor and an electrification part are replaceably accommodated in a unified process cartridge. If a toner within the toner hopper in the process cartridge runs short, a new process cartridge is inserted for use.
However, such prior art has entailed problems which follow.
That is, the elements constituting the process cartridge do not have the same life, and hence the live of the entire process cartridge is designed to conform to that of the part having the shortest life. Even if still serviceable elements remained in this process cartridge, the entire of the process cartridge including these elements had to be replaced with a new one. For example, the life of the development roller is about 5,000 sheets of record paper, whereas the life of the photoreceptor is about 30,000 sheets of record paper. For this reason, the process cartridge is replaced with a new one at the time when the development roller comes to an end of the life, and therefore the still serviceable photoreceptor is also replaced together with the development roller. Since the still serviceable elements had also to be replaced with a new one in the prior art in this manner, effective utilization of resources is not achieved with economical burden upon users more than needed.
It is possible to solve such a drawback by separating the process cartridge into a plurality of units based on respective elements or components so that only necessary units can be replaced with new ones in compliance with the lives of the respective elements.
However, such means has caused another problem which follow.
That is, in the case where such a structure is adopted that the process cartridge can be separated into the plurality of units, a unit replacement of the development roller having shorter life than the other elements frequently occurs as compared with a unit replacement of the photoreceptor having relatively long life. On the other hand, it is necessary to retain an interval between the development roller and the photoreceptor at a predetermined distance in order to maintain image quality. For this reason, the unit of the development roller inside the apparatus must be in a state of press contact with the unit of the photoreceptor. However, if the development roller unit undergoes the mounting or dismounting while being in press contact with the photoreceptor unit, operability will markedly be impaired when the development roller unit is inserted into or drown out from an apparatus main body. On the contrary, in order to ensure the operability upon the inserting or drawing out of the development roller relative to the apparatus main body, if an arrangement is employed in which the development roller unit can be mounted on or dismounted from the photoreceptor unit with a margin, it is difficult to put the development roller unit in a state of coming into press contact with the photoreceptor unit inside the apparatus. Thus, the quality of images to be developed may become degraded.
It is an object of the present invention to provide a process cartridge and an image forming apparatus using the same, the process cartridge being separated into a plurality of units depending on the lives of constituent elements so that required elements can be replaced with new ones, to thereby achieve an effective utilization of resources with reduced economic burdens on users, the process cartridge even though the development roller and the photoreceptor are separately accommodated in different units, ensuring a smooth inserting/drawing out operation of the development roller unit and assuring an appropriate distance between the development roller and the photoreceptor inside the apparatus.
According to an aspect of the present invention, the process cartridge is separated into a first unit including the photoreceptor and a second unit including the development roller, the second unit being provided with an operation member capable of moving in a unit inserting/drawing out direction, wherein when the operation member is thrust in the direction to mount the unit, the second unit is pressed against the first unit, and wherein when the operation member is drawn out to the unit dismounting direction, pressing of the second unit against the first unit is released.